The complex concept of food sustainability has become crucial in all spheres of life. Dietitians, food scientists, and technologists are in a unique position to promote sustainability in food systems. However, the perceptions of food sustainability among food science professionals and college students are under-researched, particularly in Spain. The aim of this study was therefore to analyze perceptions related to food and to food sustainability in a sample of Human Nutrition and Dietetics (HND) and Food Science and Technology (FST) students in Barcelona (Spain). An exploratory and descriptive cross-sectional study was carried out using qualitative and quantitative methodology and convenience sampling. Two focus groups and an online questionnaire were conducted (300 participants completed the survey, 151 from HND and 149 from FST). Although the students expressed concern about food sustainability, their dietary choices were primarily associated with or influenced by taste/pleasure and health/nutrition. The issue of sustainability seemed more internalized by women than men, whereas the generalized conception of a sustainable diet was essentially based on environmental aspects, with socioeconomic dimensions largely overlooked. The concept of sustainability should be promoted among food science students in all its multidimensionality, and actions need to be implemented that bring sustainability closer to students’ social practices, which should be incorporated into all university education and that is taught by professors duly trained in the subject.